That should work, if you have correct NAT rules defined.
Make sure that only VPN traffic is exempted from NAT.
E.G. The local n/w is 10.0.0.0/8 and remote n/w is 192.168.1.0/24 .
You should have a NAT rule something like this :
access-list 102 deny ip 10.0.0.0 0.255.255.255 192.168.1.0 0.0.0.255
access-list 102 permit ip 10.0.0.0 0.255.255.255 any
ip nat inside source list 102 interface overload
This way only "denied" traffic will be exempted from NAT.
You might wanna look at the doc :
http://cisco.com/en/US/tech/tk583/tk372/technologies_configuration_example09186a008009448f.shtml
Its a similar example using a route-map.
*Please rate if helped.
-Kanishka